A ball A moving with a speed of $99\;ms^{-1}$ collides directly with another identical ball B moving with a speed $v$ in the opposite direction, A comes to rest after the collision. If the coefficients of restitution is 0.8, the speed of B before collision, is :

Question

( A ) $81\; ms^{-2}$
( B ) $22.5\; ms^{-1}$
( C ) $90\; ms^{-1}$
( D ) $10\; ms^{-1}$